Composite Magnetic Shielding Unit for Wireless Charging Antennas
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Solution Overview
Problem
Conventional magnetic field shielding sheets fail to exhibit excellent magnetic properties across a wide range of frequencies, particularly for combo antenna units in portable devices that require both short distance wireless communication and wireless power transmission, leading to suboptimal antenna performance and durability issues due to fragmentation and cracking.
Innovation Solution
A magnetic field shielding unit comprising shredded Fe-based alloy and ferrite fragments with specific diameter distributions and curved shapes, integrated with dielectric filling and adhesive layers, to enhance flexibility and maintain magnetic permeability across different frequency bands, preventing further fragmentation and improving adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic body material is used to cover wide frequency bands, then device complexity is reduced, but magnetic properties (high permeability and low loss permeability) cannot be maintained across all frequency bands
Solution Approach 1:
The patent employs composite magnetic field shielding sheets combining multiple magnetic body materials (ferrite and amorphous alloy) with different permeability characteristics. Each material is selected to excel in specific frequency bands, and their composite structure allows the shielding sheet to maintain high permeability and low loss permeability across the entire frequency range from 10 kHz to 13.56 MHz, resolving the contradiction between device simplicity and magnetic property consistency.
2Length of stationary object
If magnetic field shielding sheet is thinned to reduce device thickness, then portability is improved, but physical properties (permeability) deteriorate due to storage, transportation, and usage conditions
Solution Approach 1:
The composite structure of ferrite and amorphous alloy provides inherent mechanical reinforcement. The combination of these materials creates a more robust shielding sheet that maintains its physical integrity and magnetic permeability even when thinned to 50 μm or less. The composite nature distributes mechanical stresses more effectively, preventing the permeability deterioration that occurs in single-material thin sheets during storage and transportation.
Solution Approach 2:
The patent designs the magnetic field shielding sheet as a thin, flexible structure with thickness of 50 μm or less. This thin-film approach improves portability and integration into portable devices while the composite material composition ensures that the sheet maintains its magnetic permeability and physical stability despite the reduced thickness, overcoming the traditional trade-off between thinness and reliability.
3Reliability
If amorphous alloy is used for magnetic field shielding, then low frequency magnetic properties are improved, but eddy current losses increase
Solution Approach 1:
The patent creates a composite shielding sheet where amorphous alloy and ferrite materials are combined in specific proportions. The amorphous alloy component provides excellent low-frequency magnetic properties with high permeability, while the ferrite component helps suppress eddy current losses. This composite approach allows the system to achieve low-frequency effectiveness without suffering from the eddy current penalty that would occur if amorphous alloy alone were used.
Solution Approach 2:
The shielding sheet is designed with spatially distributed magnetic body materials, where ferrite and amorphous alloy are arranged in specific patterns and proportions. This local quality differentiation allows different regions of the shielding sheet to address different loss mechanisms, with the composite structure optimizing both low-frequency performance and eddy current suppression simultaneously.
4Reliability
If ferrite is used for magnetic field shielding, then high frequency magnetic properties are improved, but the material becomes brittle and prone to fragmentation
Solution Approach 1:
The patent combines ferrite with amorphous alloy in a composite structure. The ferrite provides high-frequency magnetic properties with appropriate permeability characteristics, while the amorphous alloy component contributes mechanical toughness and flexibility. This composite approach mitigates the brittleness and fragmentation issues of pure ferrite while preserving its high-frequency performance advantages.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly enhances antenna characteristics by maintaining signal transmission efficiency and distance across various frequency bands, reducing magnetic loss, and improving durability by preventing fragmentation and cracking, thus ensuring consistent performance in portable devices.
Implementation Method 1
the magnetic body does not exhibit excellent magnetic properties (high permeability and low loss permeability) to cover all the frequency bands
Implementation Method 2
a first magnetic field shielding layer formed of fragments of shredded Fe-based alloy to improve the flexibility of the shielding unit and to reduce generation of eddy currents
Data Source
AI summary
A magnetic field shielding unit according to one embodiment of the present disclosure comprises: a first shielding sheet having a first magnetic field shielding layer formed of fragments of an Fe-based alloy to enhance an antenna characteristic for wireless charging in order to enhance flexibility and reduce an eddy current; and a second shielding sheet having a second magnetic field shielding layer formed of fragments of ferrite to enhance an antenna characteristic for short range communication in order to enhance the flexibility of the shielding unit. According to the present disclosure, the shielding unit is complexly configured to enhance all of the characteristics of different types of antennas operating in different frequency bands so that the shielding unit can significantly enhance the transmission/reception distance and efficiency of a signal and can be implemented to be very slim; the flexibility of the shielding is enhanced, which makes it possible to prevent additional micro-cracks of a magnetic material and fragmentation thereof, thus preventing a magnetic material and fragmentation thereof, thus preventing a magnetic permeability decrease in the operating frequency band of an antenna in advance; and the shielding unit can adhere firmly to an object having a step so that it is possible to solve a problem of separation of th shielding unit.